Underwater EMR for colorectal lesions: a systematic review with meta-analysis (with video)

Outcomes of underwater endoscopic mucosal resection for colorectal polyps-Insights from western India

INTRODUCTION

Underwater endoscopic mucosal resection (uEMR) represents an alternative to conventional EMR for resection of sessile colorectal polyps. We aimed at assessing the efficacy and safety of uEMR for sessile colorectal polyps.

METHODS

A retrospective analysis of endoscopy database was done for patients who underwent uEMR for sessile colorectal polyps more than 10 mm in size without any features of sub-mucosal invasion from two tertiary care centres in western India between January 2021 and June 2023. Exclusion criteria were other modes of endoscopic resection. Primary outcome was rate of en bloc resection. Secondary outcomes were complete resection rate, adverse events and recurrence rate.

RESULTS

During the study period, 159 patients with 261 lesions met the study inclusion. Mean lesion size was 1.935 ± 0.71 cm with most lesion located in the rectum (75, 28.73%) followed by sigmoid colon (69, 26.43%). Most lesions had a Paris 0-Is morphology (192, 73.56%). Japan NBI Expert Team (JNET) IIa pattern was seen on narrow band imaging (NBI) in 221 (84.67%) lesions. Complete resection was achieved in 98.46% lesions (257/261). En bloc resection was achieved in 91.82% (236/257) lesions. Complications were seen in 6.8%, all of which were managed endoscopically. Recurrence was seen in 3.1% of polyps on follow-up.

CONCLUSION

uEMR is a safe and efficacious technique for endoscopic resection for sessile colorectal polyps with high rates of en bloc resection for polyps more than 10 mm size.

Ultra-minimally invasive endoscopic techniques and colorectal diseases: Current status and its future

Colorectal diseases are increasing due to altered lifestyle, genetic, and environmental factors. Colonoscopy plays an important role in diagnosis. Advances in colonoscope (ultrathin scope, magnetic scope, capsule) and technological gadgets (Balloon assisted scope, third eye retroscope, NaviAid G-EYE, dye-based chromoendoscopy, virtual chromoendoscopy, narrow band imaging, i-SCAN, etc.) have made colonoscopy more comfortable and efficient. Now in-vivo microscopy can be performed using confocal laser endomicroscopy, optical coherence tomography, spectroscopy, etc. Besides developments in diagnostic colonoscopy, therapeutic colonoscopy has improved to manage lower gastrointestinal tract bleeding, obstruction, perforations, resection polyps, and early colorectal cancers. The introduction of combined endo-laparoscopic surgery and robotic endoscopic surgery has made these interventions feasible. The role of artificial intelligence in the diagnosis and management of colorectal diseases is also increasing day by day. Hence, this article is to review cutting-edge developments in endoscopic principles for the management of colorectal diseases.

Therapeutic Challenges for Gastric Neuroendocrine Neoplasms: Take It or Leave It?

Background and Objectives: Gastric neuroendocrine neoplasms (gNENs) represent rare but increasingly recognized tumors. They are distinguished into three main clinical types (type-1, type-2, and type-3) according to gastrin level and at histological evaluation in well-differentiated G1, G2, or G3 lesions, as well as poorly-differentiated lesions. Small type-1 and type-2 neoplasms with low proliferation indices demonstrated excellent survival without progression during an extended follow-up period, and for these reasons, active endoscopic observation or endoscopic resection are feasible options. On the other hand, surgery is the treatment of choice for more aggressive type-3, G3, or infiltrating neoplasms. The present study aims to comprehensively review and compare the available therapeutic strategies for gNENs. Materials and Methods: A computerized literature search was performed using relevant keywords to identify all of the pertinent articles with particular attention to gNEN endoscopic treatment. Results: In recent years, different endoscopic resective techniques (such as endoscopic mucosal dissection, modified endoscopic mucosal resection, and endoscopic full-thickness resection) have been developed, showing a high rate of complete resection for advanced and more aggressive lesions. Conclusions: Overall, gNENs represent a heterogeneous group of lesions with varying behavior which require personalized management. The non-operative approach for small type-1 gNENs seems to be feasible and should be promoted. A step-up approach with minimally invasive endoscopic therapies might be proposed, particularly for type-1 gNEN. On the other hand, it is important to recognize the negative prognostic factors in order to identify those rare cases requiring more aggressive approaches. A possible therapeutic algorithm for localized gNEN management is provided.

Outcomes for Underwater Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection of 21-30-mm Colorectal Polyps: A Feasible Study

BACKGROUND AND AIMS

This randomized controlled trial (RCT) was designed to evaluate the short-term outcomes of underwater endoscopic mucosal resection (UEMR) and endoscopic submucosal dissection (ESD) of 21-30 mm colonic polyps.

METHOD

We conducted a single-center RCT. Patients diagnosed with suspected colorectal intramucosal carcinoma (21-30 mm and adaptable for both UEMR and ESD) were randomly assigned to the UEMR and ESD groups at a 1:1 ratio. The primary endpoint was the R0 resection rate. We independently performed one-sample tests against the set threshold for each treatment. The significance level was set at p = 0.224.

RESULT

Eleven polyps each in the UEMR and ESD groups, respectively, were analyzed. The R0 resection rate (%) was 36 (95% confidence interval 11-69) and 100 (72-100) for UEMR and ESD, respectively, with a significant difference between the two groups (p = 0.002). The p-value against the set threshold for UEMR was 0.743, whereas that for ESD was < 0.001 (one-sample binomial test). The en bloc resection rates (%) were 82 (48-97) and 100 (72-100) for UEMR and ESD, respectively; however, no significant difference was observed (p = 0.167). The mean treatment time (min) was significantly shorter in the UEMR group (8 ± 6) than in the ESD group (48 ± 29) (p = 0.001).

CONCLUSION

ESD could achieve a high R0 resection rate, while the en bloc resection rate was comparable between the two treatment techniques with less burden on patients undergoing UEMR for 21-30-mm colorectal polyps.

CLINICAL TRIAL REGISTRATION

The study was registered at the Japan Registry of Clinical Trial as jRCT1030210015 and jRCT1030210177.

Cold resection for colorectal polyps: where we are and where we are going?

INTRODUCTION

Endoscopic resection of colonic precancerous lesions has been demonstrated to significantly decrease colorectal cancer (CRC) incidence and mortality. Among resection techniques, cold snare polypectomy (CSP) has been shown as a highly feasible, effective and safe option and is widely used in clinical practice, being regarded as the first-line technique for removal of small and diminutive colorectal polyps. On the other hand, conventional hot snare polypectomy (HSP) and endoscopic mucosal resection (EMR), namely the gold standard treatments for larger polyps, may be occasionally associated to complications due to electrocautery injury.

AREAS COVERED

To overcome these shortcomings of electrocautery-based resection techniques, in the last few years CSP has been increasingly assessed as a treatment option for additional indications, with a focus on nonpedunculated colorectal polyps ≥10 mm.

EXPERT OPINION

This review aims to present current and widened indications of CSP discussing the latest findings from the most remarkable studies, with an insight into technical issues, novelties and potential advances in the near future.

Underwater versus conventional EMR of large nonpedunculated colorectal lesions: a multicenter randomized controlled trial

BACKGROUND AND AIMS

Underwater EMR (UEMR) is an alternative procedure to conventional EMR (CEMR) to treat large, nonpedunculated colorectal lesions (LNPCLs). In this multicenter, randomized controlled clinical trial, we aimed to compare the efficacy and safety of UEMR versus CEMR on LNPCLs.

METHODS

We conducted a multicenter, randomized controlled clinical trial from February 2018 to February 2020 in 11 hospitals in Spain. A total of 298 patients (311 lesions) were randomized to the UEMR (n = 149) and CEMR (n = 162) groups. The main outcome was the lesion recurrence rate in at least 1 follow-up colonoscopy. Secondary outcomes included technical aspects, en bloc resection rate, R0 resection rates, and adverse events, among others.

RESULTS

There were no differences in the overall recurrence rate (9.5% UEMR vs 11.7% CEMR; absolute risk difference, -2.2%; 95% CI, -9.4 to 4.9). However, considering polyp sizes between 20 and 30 mm, the recurrence rate was lower for UEMR (3.4% UEMR vs 13.1% CEMR; absolute risk difference, -9.7%; 95% CI, -19.4 to 0). The R0 resection showed the same tendency, with significant differences favoring UEMR only for polyps between 20 and 30 mm. Overall, UEMR was faster and easier to perform than CEMR. Importantly, the techniques were equally safe.

CONCLUSIONS

UEMR is a valid alternative to CEMR for treating LNPCLs and could be considered the first option of treatment for lesions between 20 and 30 mm due to its higher en bloc and R0 resection rates. (Clinical trial registration number: NCT03567746.).

Underwater versus conventional endoscopic mucosal resection for sessile colorectal polyps: an updated systematic review and meta-analysis

BACKGROUND

underwater endoscopic mucosal resection (uEMR) without submucosal injection for sessile colorectal polyps was introduced as a new replacement for conventional EMR (cEMR). However, the optimal resection strategy remains a topic of debate. Hence, this meta-analysis was performed to compare the efficacy and safety of uEMR and cEMR in patients with sessile colorectal polyps.

METHODS

a comprehensive search of the literature from 2000 till January 2022 was performed from Medline, CENTRAL and Embase for randomized controlled trials (RCTs) comparing cEMR vs uEMR for colorectal polyps. The evaluated outcomes included en bloc resection, R0 resection, procedure time, overall bleeding and recurrence. Pooled risk ratios (RR) with 95 % confidence interval were calculated using a random effect model.

RESULTS

six studies were included, out of which four were full-text articles and two were conference abstracts. En bloc resection (RR 1.26, 95 % CI: 1.00-1.60), R0 resection (RR 1.10, 95 % CI: 0.96-1.26), overall bleeding (RR 0.85, 95 % CI: 0.54-1.34) and recurrence rate (RR 0.75, 95 % CI: 0.45-1.27) were comparable between uEMR and cEMR. However, uEMR was associated with a shorter procedure time (mean difference [MD] -1.55 minutes, 95 % CI: -2.71 to -0.39). According to the subgroup analysis, uEMR led to a higher rate of en bloc resection (RR 1.41, 95 % CI: 1.07-1.86) and R0 resection (RR 1.19, 95 % CI: 1.01-1.41) for polyps ≥ 10 mm in size.

CONCLUSION

both uEMR and cEMR have a comparable safety and efficacy. For polyps larger than 10 mm, uEMR may have an advantage over cEMR and should be the topic for future studies.

Endoscopic techniques for gastric neuroendocrine tumors: An update

Gastric neuroendocrine neoplasms (gNENs) are a rare type of gastric neoplasm, even if their frequency is increasing according to the latest epidemiologic revisions of the main registries worldwide. They are divided into three main subtypes, with different pathogeneses, biological behaviors, and clinical characteristics. GNEN heterogeneity poses challenges, therefore these neoplasms require different management strategies. Update the knowledge on the endoscopic treatment options to manage g-NENs. This manuscript is a narrative review of the literature. In recent years, many advances have been made not only in the knowledge of both the pathogenesis and the molecular profiling of gNENs but also in the endoscopic expertise towards innovative treatment options, which proved to be less aggressive without losing the capability of being radical. The endoscopic approach is increasingly applied in the field of gastrointestinal (GI) luminal neoplasms, and this is true not only for adenocarcinomas but also for gNENs. In particular, different techniques have been described for the endoscopic removal of suspected lesions, ranging from classical polypectomy (cold or hot snare) to endoscopic mucosal resection (both with “en bloc” or piecemeal technique), endoscopic submucosal dissection, and endoscopic full-thickness resection. GNENs comprise different subtypes of neoplasms with distinct management and prognosis. New endoscopic techniques offer a wide variety of approaches for GI localized neoplasms, which demonstrated to be appropriate and effective also in the case of gNENs. Correct evaluation of size, site, morphology, and clinical context allows the choice of tailored therapy in order to guarantee a definitive treatment.

Underwater versus conventional EMR for nonpedunculated colorectal lesions: a randomized clinical trial

BACKGROUND AND AIMS

Conventional endoscopic mucosal resection (CEMR) is the standard modality for removing nonpedunculated colorectal lesions. Underwater endoscopic mucosal resection (UEMR) has emerged as an alternative method. There are few comparative studies between these techniques, especially evaluating recurrence. Therefore, the purpose of this trial was to compare CEMR and UEMR for the resection of colorectal lesions with respect to efficacy, safety, and recurrence rate.

METHODS

This was a randomized controlled trial of UEMR versus CEMR for naïve and nonpedunculated lesions measuring between 10 and 40 mm. The primary outcome was adenoma recurrence at 6 months after the resection. Secondary outcomes were rates of technical success, en bloc resection, and adverse events. Block randomization was used to assign patients. Tattooing was performed to facilitate localization of the scars and eventual recurrences. Endoscopic follow-up was scheduled at 6 months after the procedure. The sites of resections were examined with white-light imaging, narrow-band imaging (NBI), and conventional chromoscopy with indigo carmine followed by biopsies.

RESULTS

One hundred five patients with 120 lesions were included, with a mean size of 17.5 ± 7.1 (SD) mm. Sixty-one lesions were resected by UEMR and 59 by CEMR. The groups were similar at baseline regarding age, sex, average size, and histologic type. Lesions in the proximal colon in the CEMR group corresponded to 83% and in the UEMR group to 67.8% (P = .073). There was no difference between groups regarding success rate (1 failure in each group) and en bloc resection rate (60.6% UEMR vs 54.2% CEMR, P = .48). Intraprocedural bleeding was observed in 5 CEMRs (8.5%) and 2 UEMRs (3.3%) (P = .27). There was no perforation or delayed hemorrhage in either groups. Recurrence rate was higher in the CEMR arm (15%) than in the UEMR arm (2%) (P = .031). Therefore, the relative risk of 6-month recurrence rate in the CEMR group was 7.5-fold higher (95% CI, 0.98-58.20), with a number needed to treat of 7.7 (95% CI, 40.33-4.22). The higher recurrence rate in the CEMR group persisted only for lesions measuring 21 to 40 mm (35.7% vs 0%; P = .04).

CONCLUSION

This study demonstrated that UEMR was associated with a lower adenoma recurrence rate than was CEMR. Both endoscopic techniques were effective and had similar rates of adverse events for the treatment of nonpedunculated colorectal lesions.

Cap-assisted EMR versus standard inject and cut EMR for treatment of large colonic laterally spreading tumors: a randomized multicenter study (with videos)

BACKGROUND AND AIMS

Piecemeal EMR of colorectal laterally spreading tumors (LSTs) >20 mm is effective. Experience is limited in the use of cap-assisted EMR (EMR-C) for resection of colonic lesions. We compared the efficacy and the safety of EMR-C for the removal of colonic LSTs ≥30 mm with "inject-and-cut" standard EMR (EMR-S).

METHODS

In this randomized trial from 4 Italian centers, 138 patients were treated with EMR-C and 102 with EMR-S. The rates of residual lesions, percentage of recurrence after 12 months, and adverse events were evaluated.

RESULTS

One hundred forty-three lesions were resected with EMR-C and 102 with EMR-S. Argon plasma coagulation (APC) was used as adjunctive treatment in 2.9% of EMR-Cs and in 22.5% of EMR-Ss (P < .001). The median time required was 20 minutes for EMR-C and 30 minutes for EMR-S (P < .001). Adverse events (AEs) occurred in 14 EMR-Cs (10.1%; 2 perforations, 11 bleeding events, and 1 stenosis) and in 22 EMR-Ss (21.6%; 1 perforation and 21 bleeding events) (P = .017). Intraprocedural AEs occurred in 3.6% of EMR-Cs and 16.7% of EMR-Ss (P = .001). Overall, residual lesions within 12 months were found to be significantly higher with EMR-S (32 patients, 31.4%) than with EMR-C (8 patients, 5.8%) (P < .001). Recurrence at follow-up colonoscopy in 12 months occurred in 7 EMR-Cs (5.1%) and 17 EMR-Ss (16.7%; P < .001).

CONCLUSIONS

The study demonstrated the feasibility and safety of EMR-C for removing large colorectal LSTs, with higher eradication rates, shorter resection time, and less use of APC when compared with EMR-S. (Clinical trial registration number: NCT03498664.).

Underwater versus conventional endoscopic mucosal resection for superficial non-ampullary duodenal epithelial tumors ≤20mm: A systematic review and meta-analysis

BACKGROUND AND AIMS

Underwater endoscopic mucosal resection (UEMR) is an emerging technique for endoscopic resection of superficial non-ampullary duodenal epithelial tumors (SNADETs). However, compared to conventional EMR, its efficacy and safety has not been widely explored.

METHODS

We conducted a comprehensive search using the Pubmed, Embase, and Cochrane Library databases to identify studies comparing the efficacy and safety of UEMR versus EMR for SNADETs. The main outcomes examined included en bloc resection rate, R0 resection rate, recurrence rate, procedure time, and adverse events.

RESULTS

A total of 5 studies comprising 635 patients were included. All the literature included duodenal lesions smaller than 20 mm. The pooled analysis showed that UEMR could achieve a higher en bloc resection rate (OR 1.78, 95%CI: 1.17 to 2.71, P = 0.007) and shorter procedure time (MD -4.08, 95%CI: -6.44 to -1.73, P = 0.0007) than EMR. However, the pooled results did not support a superiority of UEMR over EMR for R0 resection rate (OR 1.27; 95% CI: 0.90 to 1.81, P = 0.18) or recurrence rate (OR 0.49; 95% CI: 0.15 to 1.67, P = 0.26). The occurrence of adverse events, including postoperative bleeding, intraoperative perforation, and delayed perforation, was very low in included studies.

CONCLUSION

Compared to EMR, UEMR is an effective and safe technique for SNADETs ≤20 mm.

Underwater versus conventional cold snare polypectomy of colorectal polyps 4-9 mm in diameter: a prospective randomized controlled trial

BACKGROUND AND AIMS

Cold snare polypectomy (CSP) has been reported as safe and effective method for the removal of small colorectal polyps. However, some studies showed low R0 resection rate. Underwater endoscopic mucosal resection is an effective technique to increase the proportions of complete resection. Therefore, the aim was to compare the rate of R0 resection of colorectal polyps 4-9 mm in diameter between conventional CSP (C-CSP) and underwater CSP (U-CSP).

METHODS

This study was a prospective randomized controlled trial. A total of 198 polyps (4-9 mm) in 110 patients were enrolled between December 2019 and June 2020. The polyps were randomized to be treated with either C-CSP (100 polyps) or U-CSP (98 polyps).

RESULTS

The R0 resection rate was significantly higher in U-CSP group than in C-CSP groups (84.7% vs. 59.0%; p < 0.001). The polyp retrieval rate of C-CSP and U-CSP was 94.5% and 100% (p = 0.030). The rate of polyp fragmentation of C-CSP and U-CSP group was 5.3% and 0% (p = 0.027). The resection time and retrieval time were longer in C-CSP than U-CSP (45.0 ± 37.7 s vs. 34.1 ± 21.2 s, p = 0.032 and 51.9 ± 67.7 s vs. 12.7 ± 12.4 s, p < 0.001). No clinically significant bleeding or perforation occurred in either group.

CONCLUSIONS

The results of this study were excellent with U-CSP of 4-9 mm colorectal polyps in terms of R0 resection, polyp retrieval and fragmentation rate, and procedure/retrieval time. Therefore, U-CSP is a safe and effective technique for removing colorectal polyps 4-9 mm in diameter. KCT (0004530).

Depth of the cutting plane with underwater and conventional endoscopic mucosal resection: Post-hoc analysis of a randomized study

BACKGROUND AND AIM

A multicenter randomized controlled trial reported a better R0 resection rate for intermediate-sized (10-20 mm) colorectal polyps with underwater endoscopic mucosal resection (UEMR) than conventional endoscopic mucosal resection (CEMR). To clarify whether UEMR removes enough submucosal tissue in the removal of unpredictable invasive cancers, we investigated the cutting plane depth with UEMR versus CEMR.

METHODS

This was a post-hoc analysis of a randomized controlled trial in which 210 intermediate-sized colorectal polyps were removed in five Japanese hospitals. One pathologist and two gastroenterologists independently reviewed all resected specimens and measured the cutting plane depth. The cutting plane depth was evaluated as (i) maximum depth of submucosal layer and (ii) mean depth of submucosal layer, calculated using a virtual pathology system.

RESULTS

We identified 168 appropriate specimens for the evaluation of the cutting plane depth, resected by UEMR (n = 88) and CEMR (n = 80). The median resection depth was not significantly different between UEMR and CEMR specimens, regardless of the measurement method ([i] 1317 vs 1290 μm, P = 0.52; [ii] 619 vs 545 μm, P = 0.32). All specimens in the UEMR and CEMR groups contained substantial submucosa and no muscularis propria.

CONCLUSIONS

The cutting plane depth with UEMR was comparable with that with CEMR. UEMR can be a viable alternative method that adequately resects the submucosal layer for the histopathological assessment of unpredictable submucosal invasive cancers.

Is underwater endoscopic mucosal resection of colon polyps superior to conventional techniques? A network analysis of endoscopic mucosal resection and submucosal dissection

Background and study aims  Evidence from recent trials comparing conventional endoscopic mucosal resection (EMR) to underwater EMR (UEMR) have matured. However, studies comparing UEMR to endoscopic submucosal dissection (ESD) are lacking. Hence, we sought to conduct a comprehensive network meta-analysis to compare the efficacy of UEMR, ESD, and EMR. Methods  Embase and Medline databases were searched from inception to December 2020 for articles comparing UEMR with EMR and ESD. Outcomes of interest included rates of en bloc and complete polyp resection, risk of perforation and bleeding, and local recurrence. A network meta-analysis comparing all three approaches was conducted. In addition, a conventional comparative meta-analysis comparing UEMR to EMR was performed. Analysis was stratified according to polyp sizes (< 10 mm, ≥ 10 mm, and ≥ 20 mm). Results  Twenty-two articles were included in this study. For polyps ≥ 10 mm, UEMR was inferior to ESD in achieving en bloc resection ( P  = 0.02). However, UEMR had shorter operating time for polyps ≥ 10 mm ( P  < 0.001), and ≥20 mm ( P  = 0.019) with reduced perforation risk for polyps ≥ 10 mm ( P  = 0.05) compared to ESD. In addition, en bloc resection rates were similar between UEMR and EMR, although UEMR had reduced recurrence for polyps ≥ 10 mm ( P  = 0.013) and ≥ 20 mm ( P  = 0.014). UEMR also had shorter mean operating than EMR for polyps ≥ 10 mm ( P  < 0.001) and ≥ 20 mm ( P  < 0.001). Risk of bleeding and perforation with UEMR and EMR were similar for polyp of all sizes. Conclusions  UEMR has demonstrated technical and oncological outcomes comparable to ESD and EMR, along with a desirable safety profile. UEMR appears to be a safe and effective alternative to conventional methods for resection of polyps ≥ 10 mm.

Modified endoscopic mucosal resection techniques for treating precancerous colorectal lesions

Endoscopic mucosal resection (EMR) is a technique allowing efficacious and minimally invasive resection of precancerous lesions across the entire gastrointestinal tract. However, conventional EMR, involving injection of fluid into the submucosal space, is imperfect, given the high rate of recurrence of post-endoscopic resection adenoma, especially after piecemeal resection. In light of these observations, modifications of the technique have been proposed to overcome the weakness of conventional EMR. Some of them were designed to maximize the chance of en bloc resection—cap-assisted EMR, underwater EMR, tip-in EMR, precutting, assisted by ligation device—while others were designed to minimize the complications (cold EMR). In this review, we present their modes of action and summarize the evidence regarding their efficacy and safety.

EVALUATION OF UNDERWATER ENDOSCOPIC MUCOSAL RESECTION FOR COLORECTAL POLYPS IN AN OUTPATIENT CLINIC IN BRAZIL

BACKGROUND

Since 2012, a new technique for resection of large polyps has been described, the underwater endoscopic mucosal resection (UEMR). Some advantages that emerge from it is the needless of injection in submucosal layer and a greater chance of complete capture of the polyp.

OBJECTIVE

There are few studies of UEMR in Brazil. The aim of this study is to evaluate the safety and efficacy of this technique in one Brazilian center.

METHODS

This case series was conducted from February to December of 2020. Colorectal polyps greater than 9 mm without features of deep submucosal invasion were resected using UEMR.

RESULTS

Twenty-four large polyps were resected with the UEMR approach from 24 patients. The mean size of the polys was 19 mm, ranging from 12 to 35 mm. All lesions were successful resected and 66% (16/24) were resected en bloc. In histologic analyses, most of them were adenomas (70.8%) and only one had deep submucosal invasion. There were no cases of acute complications, such perforation or acute bleeding.

CONCLUSION

The UEMR is a safe and feasible procedure. With the emerging data on the procedure, it seems to be a wonderful tool in preventing colorectal cancer and its applicability and scope should be encourage to surpass reference centers.

Heat sink effect of underwater polypectomy in a porcine colon model

BACKGROUND

Underwater polypectomy without the need for submucosal injection has been reported. A heat-sink effect by immersing the polyp in water was proposed but no such experiment has been performed to support the claim. We compared the temperature rise on the serosal side during polypectomy between air- and water-filled colon.

METHOD

Freshly harvested porcine colons were placed in a metal tray with cautery electrode pad attached to its bottom. An upper endoscope was used with a cap and a rubber band mounted to the distal end. A mucosal site was randomly selected and identified on its serosal surface with a marker while suction was applied. Suction was applied again and a ligation band was applied to create a polyp. A cautery snare grasped the artificial polyp just below the band. An assistant placed the tip of a thermometer at the marked site on the serosal surface to record the baseline temperature before cautery and the highest temperature during polypectomy. Seven polypectomies in air and underwater were performed.

RESULTS

Mean (standard deviation) baseline temperature were 23.3 (0.6) °C and 23.4 (0.6) °C in the air and water groups, respectively. The maximum rise in temperature during polypectomy was 6.1 (4.5) °C and 1.4 (1.0) °C in the air and water groups, respectively (P = 0.004).

CONCLUSIONS

The maximum temperature rise during polypectomy was significantly less when polypectomy was performed underwater, supporting the hypothesis that a heat-sink effect does exist during underwater polypectomy.

Curative value of underwater endoscopic mucosal resection for submucosally invasive colorectal cancer

BACKGROUND AND AIM

Occasionally, colorectal tumors without characteristics of deep submucosal invasion are found to be invasive upon pathological evaluation after endoscopic resection (ER). Because the resection depth for underwater endoscopic mucosal resection (UEMR) has not been clarified, we evaluated the feasibility of UEMR for pathologically invasive colorectal cancer (pT1-CRC).

METHODS

We retrospectively investigated data on the backgrounds and outcomes of patients with pT1-CRC who underwent UEMR between January 2014 and June 2019 at our institute. As a reference standard, the backgrounds and outcomes of pT1-CRCs that had undergone conventional EMR (CEMR) were also investigated.

RESULTS

Thirty-one patients (median age, 68 years [range, 32-88 years]; 22 men [71%]) were treated with UEMR. Median lesion size was 17 mm (range, 6-50 mm). The endoscopic complete resection rate was 100%. The overall en bloc resection rate was 77%, and the VM0, HM0, and R0 resection rates were 81%, 58%, and 55%, respectively. In cases of pT1a (invasion <1000 μm)-CRC (n = 14), the en bloc, VM0, and R0 resection rates were 92%, 100%, and 71%, respectively. Seventeen patients (five with risk factors for lymph node metastasis and 12 without) were followed up, and no local recurrence and distant metastasis were observed during the follow-up period (median follow-up period, 18 months [range, 6-62 months]) after UEMR. The outcomes of UEMR seemed to be comparable with those of CEMR (n = 32).

CONCLUSIONS

The VM0 rate of UEMR for pT1-CRC, especially for pT1a-CRC, without characteristics of deep submucosal invasion seems feasible.

Efficacy and histologic accuracy of underwater versus conventional endoscopic mucosal resection for large (>20 mm) colorectal polyps: a comparative review and meta-analysis

BACKGROUND AND AIMS

Major limitations with conventional EMR (C-EMR) include high rates of polyp recurrence and low en-bloc resection rates, especially for lesions >20 mm in size. Underwater EMR (U-EMR) has emerged as an alternate technique for en-bloc resection of larger lesions. We conducted a systematic review and meta-analysis comparing the efficacy and safety of the 2 techniques.

METHODS

Multiple databases were searched through June 2020 for studies that compared outcomes of U-EMR and C-EMR for colorectal lesions. Meta-analysis was performed to determine pooled odds ratios (ORs) of successful R0, en-bloc, and piecemeal resection of colorectal lesions. We compared the rates of polyp recurrence at follow-up, diagnostic accuracy for colorectal cancer, and adverse events with the 2 techniques.

RESULTS

Eleven studies, including 4 randomized controlled trials (RCTs) with 1851 patients were included in the final analysis. A total of 1071 lesions were removed using U-EMR, and 1049 lesions were removed using C-EMR. Although U-EMR had an overall superior en-bloc resection rate compared with C-EMR (OR, 1.9; 95% confidence interval [CI], 1-3.5; P = .04), both techniques were comparable in terms of polyps >20 mm in size (OR, 0.8; 95% CI, 0.3-2.1; P = .75), R0 resection (OR, 3.1; 95% CI, 0.74-12.6; P = .14), piecemeal resection (OR, 3.1; 95% CI, 0.74-12.6; P = .13), and diagnostic accuracy for colorectal cancer (OR, 1.1; 95% CI, 0.6-1.8; P = .82). There were lower rates of polyp recurrence (OR, 0.3; 95% CI, 0.1-0.8; P = .01) and incomplete resection (OR, 0.4; 95% CI, 0.2-0.5; P = .001) with U-EMR. Both techniques have comparable resection times and safety profiles.

CONCLUSIONS

Our results support the use of U-EMR over C-EMR for successful resection of colorectal lesions. Further randomized controlled trials are needed to evaluate the efficacy of U-EMR for resecting polyps >20 mm in size.

Indications and outcomes of endoscopic resection for non-pedunculated colorectal lesions: A narrative review

In the last years, endoscopic techniques gained a crucial role in the treatment of colorectal flat lesions. At the same time, the importance of a reliable assessment of such lesions to predict the malignancy and the depth of invasion of the colonic wall emerged. The current unsolved dilemma about the endoscopic excision techniques concerns the necessity of a reliable submucosal invasive cancer assessment system that can stratify the risk of the post-procedural need for surgery. Accordingly, this narrative literature review aims to compare the available diagnostic strategies in predicting malignancy and to give a guide about the best techniques to employ. We performed a literature search using electronic databases (MEDLINE/PubMed, EMBASE, and Cochrane Library). We collected all articles about endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) registering the outcomes. Moreover, we analyzed all meta-analyses comparing EMR vs ESD outcomes for colorectal sessile or non-polypoid lesions of any size, preoperatively estimated as non-invasive. Seven meta-analysis studies, mainly Eastern, were included in the analysis comparing 124 studies and overall 22954 patients who underwent EMR and ESD procedures. Of these, eighty-two were retrospective, twenty-four perspective, nine case-control, and six cohorts, while three were randomized clinical trials. A total of 18118 EMR and 10379 ESD were completed for a whole of 28497 colorectal sessile or non-polypoid lesions > 5-10 mm in size. In conclusion, it is crucial to enhance the preoperative diagnostic workup, especially in deciding the most suitable endoscopic method for radical resection of flat colorectal lesions at risk of underlying malignancy. Additionally, the ESD necessitates further improvement because of the excessively time-consuming as well as the intraprocedural technical hindrances and related complications. We found a higher rate of en bloc resections and R0 for ESD than EMR for non-pedunculated colorectal lesions. Nevertheless, despite the lower local recurrence rates, ESD had greater perforation rates and needed lengthier procedural times. The prevailing risk for additional surgery in ESD rather than EMR for complications or oncologic reasons is still uncertain.

Efficacy of Underwater Endoscopic Mucosal Resection for Nonpedunculated Colorectal Polyps: A Systematic Review and Meta-Analysis

Recently, underwater endoscopic mucosal resection (UEMR) without submucosal injection was introduced as a new replacement for conventional EMR (CEMR) and was reported to be useful for resecting large colonic polyps. Here, we aimed to assess the efficacy and safety of these two methods by a systematic review and meta-analysis. We comprehensively searched multiple databases until July 2021 to identify randomized controlled trials (RCTs) comparing UEMR with CEMR. The primary outcomes were the proportion of R0 resection and mean procedure time, and the secondary outcomes were the proportion of en bloc resection and all adverse events. Three reviewers independently searched for articles, extracted data, and assessed the risk of bias. We evaluated the certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation approach. This study was registered in www.protocols.io (Protocol Integer ID: 40849). We included six RCTs (1,374 polyps). We judged that a meta-analysis was not available, and the data were summarized narratively for the proportion of R0 resection. Regarding procedure time, UEMR likely resulted in a large reduction (mean difference = -64.3 seconds; 95% confidence interval (CI) = -122.5 to -6.0 seconds; I2 = 86%; moderate certainty of evidence). UEMR likely resulted in a large increase in en bloc resection (odds ratio = 1.85; 95% CI = 1.15 to 2.98; I2 = 60%; moderate certainty of evidence). Percentages of adverse events were 0-17% with CEMR and 0-16% with UEMR. In summary, UEMR might have higher efficacy than CEMR in the endoscopic resection of nonpedunculated colorectal polyps, with likely a large reduction in procedure time.

Higher rate of en bloc resection with underwater than conventional endoscopic mucosal resection: A meta-analysis

OBJECTIVES

Previous meta-analysis including nonrandomized studies showed marginal benefit of underwater endoscopic mucosal resection(U-EMR) compared to conventional EMR(C-EMR) in terms of polypectomy outcomes. We evaluated U-EMR compared to C-EMR in the treatment of colorectal polyps with respect to effectiveness and safety by analyzing only randomized controlled trials(RCTs).

MATERIAL AND METHODS

PubMed and Cochrane Library databases were searched for RCTs published until 11/2020, evaluating U-EMR vs. C-EMR regarding en bloc resection, post-endoscopic resection adenoma recurrence, complete resection, adverse events rates and difference in resection time. Abstracts from Digestive Disease Week, United European Gastroenterology Week and ESGE Days meetings were also searched. Effect size on outcomes is presented as risk ratio(RR; 95% confidence interval[CI]) or mean difference(MD; 95%CI). The I2 test was used for quantifying heterogeneity, while Grading of Recommendations Assessment, Development and Evaluation(GRADE) was used to assess strength of evidence.

RESULTS

Six RCTs analyzing outcomes from 1157 colorectal polypectomies(U-EMR589;C-EMR,568) were included. U-EMR associated with significant higher rate of en bloc resection compared to C-EMR [RR(95%CI):1.26(1.01-1.58); Chi² for heterogeneity=30.43, P<0.0001; I²=84%, GRADE: Very low]. This effect was more prominent regarding resection of polyps sized ≥20 mm compared to polyps <20 mm [RR(95%CI):1.64(1.22-2.20) vs. 1.10(0.98-1.23)]. Post-resection recurrence [RR(95%CI):0.52(0.28-0.94);GRADE:Low] was lower significantly in U-EMR group. In contrast, no significant difference was detected between U-EMR and C-EMR regarding complete resection [RR(95%CI): 1.06(0.91-1.24) GRADE:Very low] and adverse events occurrence[RR(95%CI):1.00 (0.72-1.39); GRADE:Low].

CONCLUSION

Meta-analysis of RCTs supports that U-EMR resection achieves higher rate of en bloc resection compared to conventional EMR. This effect is driven when resecting large(≥20 mm) polyps.

Water-assisted colonoscopy: an international modified Delphi review on definitions and practice recommendations

BACKGROUND AND AIMS

Since 2008, a plethora of research studies has compared the efficacy of water-assisted (aided) colonoscopy (WAC) and underwater resection (UWR) of colorectal lesions with standard colonoscopy. We reviewed and graded the research evidence with potential clinical application. We conducted a modified Delphi consensus among experienced colonoscopists on definitions and practice of water immersion (WI), water exchange (WE), and UWR.

METHODS

Major databases were searched to obtain research reports that could potentially shape clinical practice related to WAC and UWR. Pertinent references were graded (Grading of Recommendations, Assessment, Development and Evaluation). Extracted data supporting evidence-based statements were tabulated and provided to respondents. We received responses from 55 (85% surveyed) experienced colonoscopists (37 experts and 18 nonexperts in WAC) from 16 countries in 3 rounds. Voting was conducted anonymously in the second and third round, with ≥80% agreement defined as consensus. We aimed to obtain consensus in all statements.

RESULTS

In the first and the second modified Delphi rounds, 20 proposed statements were decreased to 14 and then 11 statements. After the third round, the combined responses from all respondents depicted the consensus in 11 statements (S): definitions of WI (S1) and WE (S2), procedural features (S3-S5), impact on bowel cleanliness (S6), adenoma detection (S7), pain score (S8), and UWR (S9-S11).

CONCLUSIONS

The most important consensus statements are that WI and WE are not the same in implementation and outcomes. Because studies that could potentially shape clinical practice of WAC and UWR were chosen for review, this modified Delphi consensus supports recommendations for the use of WAC in clinical practice.

The efficacy and safety of underwater endoscopic mucosal resection for ≥10-mm colorectal polyps: systematic review and meta-analysis

BACKGROUND

Underwater endoscopic mucosal resection (UEMR) is a promising strategy for nonpedunculated colorectal polyp removal. However, the efficacy and safety of the technique for the treatment of ≥ 10-mm colorectal polyps remain unclear. We aimed to comprehensively assess the efficacy and safety of UEMR for polyps sized 10-19 mm and ≥ 20 mm.

METHODS

PubMed, EMBASE, and the Cochrane Library databases were searched for relevant articles from January 2012 to November 2019. Primary outcomes were the rates of adverse events and residual polyps. Secondary outcomes were the complete resection, en bloc resection, and R0 resection rates.

RESULTS

18 articles including 1142 polyps from 1093 patients met our inclusion criteria. The overall adverse event and residual polyp rates were slightly lower for UEMR when removing colorectal polyps of 10-19 mm vs. ≥ 20 mm (3.5 % vs. 4.3 % and 1.2 % vs. 2.6 %, respectively). The UEMR-related complete resection rate was slightly higher for colorectal polyps of 10-19 mm vs. ≥ 20 mm (97.9 % vs. 92.0 %). However, the en bloc and R0 resection rates were dramatically higher for UEMR removal of polyps of 10-19 mm vs. ≥ 20 mm (83.4 % vs. 36.1 % and 73.0 % vs. 40.0 %, respectively). In addition, univariate meta-regression revealed that polyp size was an independent predictor for complete resection rate (P = 0.03) and en bloc resection (P = 0.01).

CONCLUSIONS

UEMR was an effective and safe technique for the removal of ≥ 10-mm nonpedunculated colorectal polyps. However, UEMR exhibited low en bloc and R0 resection rates for the treatment of ≥ 20-mm polyps.

Underwater Endoscopic Mucosal Resection for 10 mm or Larger Nonpedunculated Colorectal Polyps: A Systematic Review and Meta-Analysis

Background/Aims

Recent studies have reported the favorable outcomes of underwater endoscopic mucosal resection (UEMR) for colorectal polyps. We performed a systematic review and meta-analysis evaluating the efficacy and safety of UEMR for nonpedunculated polyps ≥10 mm.

Methods

We performed a comprehensive search of multiple databases (through May 2020) to identify studies reporting the outcomes of UEMR for ≥10 mm nonpedunculated colorectal polyps. The assessed outcomes were recurrence rate on the first follow-up, en bloc resection, incomplete resection, and adverse events after UEMR.

Results

A total of 1276 polyps from 16 articles were included in our study. The recurrence rate was 7.3% (95% confidence interval [CI], 4.3–12) and 5.9% (95% CI, 3.6–9.4) for nonpedunculated polyps ≥10 and ≥20 mm, respectively. For nonpedunculated polyps ≥10 mm, the en bloc resection, R0 resection, and incomplete resection rates were 57.7% (95% CI, 42.4–71.6), 58.9% (95% CI, 42.4–73.6), and 1.5% (95% CI, 0.8–2.6), respectively. The rates of pooled adverse events, intraprocedural bleeding, and delayed bleeding were 7.0%, 5.4%, and 2.9%, respectively. The rate of perforation and postpolypectomy syndrome was 0.8%.

Conclusions

Our systematic review and meta-analysis demonstrates that UEMR for nonpedunculated colorectal polyps ≥10 mm is safe and effective with a low rate of recurrence.

Underwater endoscopic mucosal resection of adenomas and colorectal serrated lesions: a prospective clinical study

Background

Underwater endoscopic mucosal resection (UEMR) without submucosal injection has been described as an alternative technique to the endoscopic resection of adenomas and colorectal serrated lesions. We aimed to assess the feasibility, safety, and efficacy of UEMR in a Brazilian setting.

Methods

This was a prospective observational study of consecutive patients who underwent UEMR between January and July 2019, in a single tertiary care center. Inclusion criteria were lesions without endoscopic stigmata of deep submucosal invasion in patients referred for endoscopic resection of colorectal adenomas, and serrated lesions detected in a previous colonoscopy. The following features were assessed: complete resection rate, en bloc resection rate, resection time, adverse events, and resection infeasibility.

Results

A total of 36 patients underwent UEMR for 51 colorectal lesions. The mean/median lesion size was 16.24/13 mm and the mean/median resection time was 16.97/9.19 min. Histopathology revealed the following: tubular adenoma (43.1%), tubulovillous adenoma (13.7%), serrated lesions (41.2%), and intramucosal adenocarcinoma (2%). Complete resection was achieved in 86.3% of cases; 52.9% of the lesions were removed en bloc, while 47.1% were resected in a piecemeal fashion. UEMR was feasible in 96.1% of cases and failed on 2 occasions, requiring conversion to standard endoscopic mucosal resection. Minor intraoperative bleeding occurred in 5 patients (9.8%) and only 1 presented with delayed bleeding (2%), all controlled endoscopically.

Conclusion

UEMR for removal of adenomas and colorectal serrated lesions was demonstrated to be feasible, safe and effective.

Underwater versus conventional EMR for colorectal polyps: systematic review and meta-analysis

BACKGROUND AND AIMS

Underwater EMR (UEMR) has emerged as an attractive alternative to conventional EMR (CEMR) for the resection of colorectal polyps. The purpose of this systematic review and meta-analysis was to compare UEMR and CEMR for the resection of colorectal polyps with respect to efficacy and safety.

METHODS

A literature search was performed across multiple databases, including MEDLINE/PubMed, The Cochrane Library, CINAHL, Google Scholar, and Scopus, for studies that were published until May 2020. Only studies that compared the resection of colorectal polyps using UEMR with CEMR were included. Outcomes examined included rates of en bloc resection, recurrence, postprocedure bleeding, perforation, and resection time.

RESULTS

Seven studies totaling 1237 polyps were included: 614 polyps were resected with UEMR and 623 polyps with CEMR. UEMR was associated with a significant increase in the rate of overall en bloc resection (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.42-2.39; P < .001; I² = 38%), with subgroup analysis showing a significant increase in the rates of en bloc resection in polyps ≥20 mm (OR, 1.51; 95% CI, 1.06-2.14; P = .02; I² = 44%) but not in polyps <20 mm (OR, 1.07; 95% CI, .65-1.76; P = .80; I² = 27%), and with a significant reduction in the rate of recurrence (OR, .30; 95% CI, .16-.57; P = .0002; I² = 0%), again driven by improvements in polyps ≥20 mm. There was no significant difference in postprocedure bleeding (OR, 1.11; 95% CI, .57-2.17; P = .76; I² = 0%) or perforation (OR, .72; 95% CI, .19-2.83; P = .64; I² = 0%).

CONCLUSIONS

The results of this systematic review and meta-analysis demonstrate that UEMR is a safe and efficacious alternative to CEMR. With appropriate training, UEMR may be strongly considered as a first-line option for resection of colorectal polyps.

Room temperature water infusion during colonoscopy insertion induces rectosigmoid colon mucus production

BACKGROUND

Water filling during colonoscopy improves several colonoscopy outcomes. We evaluated an anecdotal observation that room temperature water filling during colonoscope insertion results in mucus production in the left colon, which may impair mucosal visualization during withdrawal.

METHODS

We performed 55 colonoscopies with either water or saline filling during insertion, and video recorded the examinations. Three blinded observers scored the amount of mucus visible on the video recordings.

RESULTS

29 patients had water filling and 26 patients had saline filling during insertion. Demographic features, procedure indications, volume of infused fluid, and insertion time to the cecum were similar in the two groups. All three blinded observers rated the mucus as greater after water filling than after saline (median 3 out of 5 vs. 1 out of 5; P < 0.001), with a kappa value for interobserver agreement of 0.364 (P < 0.001).

CONCLUSION

Room temperature water filling is associated with mucus production by the rectosigmoid colon, requiring additional cleansing during withdrawal.

Underwater versus conventional endoscopic mucosal resection for colorectal lesions: a systematic review and meta-analysis

Background and study aims  Underwater endoscopic mucosal resection (UEMR) for colorectal polyps has been reported to have good outcomes in recent studies. We conducted a systematic review and meta-analysis comparing the effectiveness and safety of UEMR to conventional EMR (CEMR). Methods  A comprehensive search of multiple databases (through May 2020) was performed to identify studies that reported outcome of UEMR and CEMR for colorectal lesions. Outcomes assessed included incomplete resection, rate of recurrence, en bloc resection, adverse events (AEs) for UEMR and CEMR. Results  A total of 1,651 patients with 1,704 polyps were included from nine studies. There was a significantly lower rate of incomplete resection (odds ratio [OR]: 0.19 (95 % confidence interval (CI), 0.05-0.78, P  = 0.02) and polyp recurrence (OR: 0.41, 95 % CI, 0.24-0.72, P  = 0.002) after UEMR. Compared to CEMR, rates overall complications (relative risk [RR]: 0.66 (95 % CI, 0.48-0.90) ( P  = 0.008), and intra-procedural bleeding (RR: 0.59, 95 % CI, 0.41-0.84, P  = 0.004) were significantly lower with UEMR. The recurrence rate was also lower for large non-pedunculated polyps ≥ 10 mm (OR 0.24, 95 % CI, 0.10-0.57, P  = 0.001) and ≥ 20 mm (OR 0.14, 95 % CI, 0.02-0.72, P  = 0.01). The rates of en bloc resection, delayed bleeding, perforation and post-polypectomy syndrome were similar in both groups ( P  > 0.05). Conclusions  In this systematic review and meta-analysis, we found that UEMR is more effective and safer than CEMR with lower rates of recurrence and AEs. UEMR use should be encouraged over CEMR.

Underwater vs conventional endoscopic mucosal resection in the management of colorectal polyps: a systematic review and meta-analysis

Background  Recently, underwater endoscopic mucosal resection (UEMR) has shown promising results in the management of colorectal polyps. Some studies have shown better outcomes compared to conventional endoscopic mucosal resection (EMR). We conducted this systematic review and meta-analysis to compare UEMR and EMR in the management of colorectal polyps. Methods  We searched several databases from inception to November 2019 to identify studies comparing UEMR and EMR. Outcomes assessed included rates of en bloc resection, complete macroscopic resection, recurrent/residual polyps on follow-up colonoscopy, complete resection confirmed by histology and adverse events. Pooled risk ratios (RR) with 95 % confidence interval were calculated using a fixed effect model. Heterogeneity was assessed by I ² statistic. Funnel plots and Egger's test were used to assess publication bias. We used the Newcastle-Ottawa scale (NOS) for assessment of quality of observational studies, and the Cochrane tool for assessing risk of bias for RCTs Results  Seven studies with 1291 patients were included; two were randomized controlled trials and five were observational. UEMR demonstrated statistically significantly better efficacy in rates of en bloc resection, pooled RR 1.16 (1.08, 1.26), complete macroscopic resection, pooled RR 1.28 (1.18, 1.39), recurrent/residual polyps; pooled RR 0.26 (0.12, 0.56) and complete resection confirmed by histology; pooled RR 0.75 (0.57, 0.98). There was no significant difference in adverse events (AEs); pooled RR 0.68 (0.44, 1.05). Conclusions  This meta-analysis found statistically significantly better rates of en bloc resection, complete macroscopic resection, and lower risk of recurrent/residual polyps with UEMR compared to EMR. We found no significant difference in AEs between the two techniques.

Feasibility and safety of modified underwater endoscopic mucosal resection for colorectal polyps

BACKGROUND

Conventional endoscopic mucosal resection (EMR) with submucosal injection has been widely performed to remove colorectal polyps, although it often makes sessile lesions flattened and enlarged, resulting in the failure of lesion snaring. Air deflation and water immersion during underwater EMR (UEMR) sometimes interfere with the exposure of colorectal polyps. Modified UEMR may facilitate the resection of colorectal polyps due to integrating the advantages of EMR and UEMR.

AIM

To investigate the feasibility and safety of the modified UEMR in the treatment of colorectal polyps.

METHODS

Fifty-nine patients with 76 colorectal polyps treated by modified UEMR were enrolled in the study from July 2015 to June 2019, and compared with 43 patients with 65 colorectal polyps treated by UEMR during the same period. All lesions were classified as Paris Is or IIa, and the size of the polyp ranged from 1 cm to 3 cm in diameter. Endoscopic procedure was as follows: Once observed, the polyp was completely immersed by warm water infusion. The polyp was placed in the 6 o'clock direction. Following submucosal injection with normal saline plus methylene blue, an appropriate snare was used for en bloc resection. The mucosal defect was closed with clips. The excised specimen was sent for pathological evaluation after crystal violet staining.

RESULTS

All the 76 lesions in the study group were successfully resected by modified UEMR. Among them, 64 polyps less than 2 cm in size received en bloc resection. In 12 polyps ranging 2-3 cm in size, 5 received en bloc resection and 7 received piecemeal UEMR. The overall en bloc resection rate was 91%; the rate for those polyps < 2 cm was 100%, and the rate for polyps ranging from 2 cm to 3 cm was 42%. All the 65 lesions in the control group were successfully treated by conventional UEMR. Of 58 lesions less than 2 cm in size, 49 underwent en bloc resection and the other 9 underwent additional argon plasma coagulation (APC) due to residual lesion. Of 7 lesions ranging from 2 cm to 3 cm in size, 2 underwent en bloc resection, 1 undewent additional APC due to residual lesion, and the other 5 underwent piecemeal UEMR or were converted to modified endoscopic submucosal dissection. The overall en bloc resection rate in the control group was 76%; the rate for the lesions < 2 cm was 84%, and that for lesions 2-3 cm was 14%. During operation, minor bleeding occurred in 9 patients of the study group and 13 patients of the control group. There were no complications such as delayed bleeding and perforation in either group. During the follow-up period, local recurrence was found in 2 patients of the study group, and 9 patients of the control group.

CONCLUSION

Compared with conventional UEMR, modified UEMR can provide more excellent exposure for polyps, and achieve higher en bloc resection rate by discontinuous suction during tightening of the snare, resulting in a high complete resection rate and low recurrence rate.

Effectiveness and safety of underwater techniques in gastrointestinal endoscopy: a comprehensive review of the literature

BACKGROUND

Conventional endoscopic resection techniques such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD), represent the standard of care for treatment of superficial gastrointestinal lesions. In 2012 a novel technique called underwater endoscopic mucosal resection (U-EMR) was described by Binmoeller and colleagues. This substantial variation from the standard procedure was afterwards applied at endoscopic submucosal dissection (U-ESD) and recently proposed also for peroral endoscopic myotomy (U-POEM) and endoscopic full-thickness resection (U-EFTR).

METHODS

This paper aims to perform a comprehensive review of the current literature related to supporting the underwater resection techniques with the aim to evaluate their safety and efficacy.

RESULTS

Based on the current literature U-EMR appears to be feasible and safe. Comparison studies showed that U-EMR is associated with higher "en-bloc" and R0 resection rates for colonic lesions, but lower "en-bloc" and R0 resection rates for duodenal non-ampullary lesions, compared to standard EMR. In contrast to U-EMR, little evidence supporting U-ESD are currently available. A single comparison study on gastric lesions showed that U-ESD had shorter procedural times and allowed a similar "en-bloc" resection rates compared to standard ESD. No comparison studies between U-ESD and ESD are available for colonic lesions. Finally, only some anecdotal experiences have been reported for U-POEM or U-EFTR, and the feasibility and effectiveness of these techniques need to be further investigated.

CONCLUSIONS

Further prospective studies are necessary to better explore the advantages of underwater techniques compared to the respective standards of care, especially in the setting of U-ESD where consistent data are lacking and where standardization of the technique is needed.

Efficacy and safety of underwater endoscopic mucosal resection for superficial non-ampullary duodenal epithelial tumors: a systematic review and meta-analysis

Background:

Superficial non-ampullary duodenal epithelial tumors (SNADET) are increasingly found during upper endoscopy. Underwater endoscopic mucosal resection (UEMR) is an emerging technique for the endoscopic resection of SNADET. We performed a systematic review and meta-analysis to evaluate the efficacy and safety of this technique.

Methods:

We conducted a comprehensive search of several databases from inception to August 2019, which included Ovid Cochrane Database of Systematic Reviews, Ovid Embase, Scopus, Ovid Cochrane Central Register of Controlled trials, Ovid MEDLINE^®, and In-Process and other non-indexed citations. The primary outcome assessed was the pooled clinical success rate of UEMR. Secondary outcomes included rate of en bloc resection, pooled rate of high-grade dysplasia or intramucosal carcinoma (HGIC), and pooled rate of adverse events. Meta-regression analysis was performed based on tumor size.

Results:

A total of 8 study arms were included for analysis with UEMR performed in a total of 258 lesions. The pooled clinical success rate was 89.9% (95% confidence interval [CI] 83.4-94.1). En-bloc removal was achieved in 84.6% of treated lesions (95%CI 75.5-90.7). The pooled rate of HGIC was 24.7% (95%CI 10.3-48.3). The pooled rate of adverse events was 6.9% (95%CI 2.5-17.9). This included 10 total adverse events, with the majority being self-limited delayed bleeding. There were no duodenal perforations.

Conclusions:

UEMR for endoscopic resection of SNADET has a high efficacy. In addition, this technique has a high rate of en bloc resection and an acceptable adverse event profile. Given these data, UEMR should be considered as a method for endoscopic resection of SNADET.

UNDERWATER ENDOSCOPIC MUCOSAL RESECTION FOR NON-PEDUNCULATED COLORECTAL LESIONS. A PROSPECTIVE SINGLE-ARM STUDY

BACKGROUND

Underwater endoscopic mucosal resection (UEMR) has emerged as a revolutionary method allowing resection of colorectal lesions without submucosal injection. Brazilian literature about this technique is sparse.

OBJECTIVE

The aim of this study was evaluate the efficacy and safety of UEMR technique for removing non-pedunculated colorectal lesions in two Brazilian tertiary centers.

METHODS

This prospective study was conducted between June 2016 and May 2017. Naïve and non-pedunculated lesions without signs of submucosal invasion were resected using UEMR technique.

RESULTS

A total of 55 patients with 65 lesions were included. All lesions, except one, were successfully and completely removed by UEMR (success rate 98.5%). During UEMR, two cases of bleeding were observed (3.0%). One patient had abdominal pain on the day after resection without pneumoperitoneum. There was no perforation or delayed bleeding.

CONCLUSION

This study supports the existing data indicating acceptable rates of technical success, and low incidence of adverse events with UEMR. The results of this Brazilian study were consistent with previous abroad studies.

Blue laser imaging and linked color imaging improve the color difference value and visibility of colorectal polyps in underwater conditions

BACKGROUND AND AIM

Underwater endoscopic mucosal resection (UEMR) has become widespread for treating colorectal polyps. However, which observational mode is best suited for determining polyp margins underwater remains unclear. To determine the best mode, we analyzed three imaging modes: white light imaging (WLI), blue laser imaging (BLI) and linked color imaging (LCI).

METHODS

Images of consecutive colorectal polyps previously examined by these three modes before UEMR were analyzed according to the degree of underwater turbidity (transparent or cloudy). Color differences between the polyps and their surroundings were calculated using the Commission Internationale d'Eclairage Lab color space in which 3-D color parameters were expressed. Eight evaluators, who were blinded to the histology, scored the visibility from one (undetectable) to four (easily detectable) in both underwater conditions. The color differences and visibility scores were compared.

RESULTS

Seventy-three polyps were evaluated. Sixty-one polyps (44 adenomatous, 17 serrated) were observed under transparent conditions, and 12 polyps (seven adenomatous, five serrated) were observed under cloudy conditions. Under transparent conditions, color differences for the BLI (8.5) and LCI (7.9) were significantly higher than that of WLI (5.7; P < 0.001). Visibility scores for BLI (3.6) and LCI (3.4) were also higher than that of WLI (3.1; P < 0.0001). Under cloudy conditions, visibility scores for LCI (2.9) and WLI (2.7) were significantly higher than that of BLI (2.2; P < 0.0001 and P = 0.04, respectively).

CONCLUSIONS

BLI and LCI were better observational modes in transparent water; however, BLI was unsuitable for cloudy conditions.

Impact of en bloc resection on long-term outcomes after endoscopic mucosal resection: a matched cohort study

BACKGROUND AND AIMS

Residual or recurrent adenoma (RRA) is the major limitation of piecemeal EMR (p-EMR) for large colonic laterally spreading lesions (LSLs) ≥20 mm. En bloc EMR (e-EMR) has been shown to achieve low rates of RRA but specific procedural and long-term outcomes are unknown. Our aim was to compare long-term outcomes of size-matched LSLs stratified by whether they were resected e-EMR or p-EMR.

METHODS

Data from a prospective tertiary referral multicenter cohort of large LSLs referred for EMR over a 10-year period were analyzed. Outcomes were compared between sized-matched LSLs (20-25 mm) resected by p-EMR or e-EMR.

RESULTS

Five hundred seventy LSLs met the inclusion criteria of which 259 (45.4%) were resected by e-EMR. The risk of major deep mural injury (DMI) was significantly higher in the e-EMR group (3.5% vs 1.0%, P = .05), whereas rates of other intraprocedural adverse events did not differ significantly. Five of 9 (56%) LSLs, with endoscopic features of submucosal invasion (SMI), resected by e-EMR were saved from surgery. RRA at first surveillance was lower in the e-EMR group (2.0% vs 5.7%, P = .04), but this difference was negated at subsequent surveillance. Rates of surgical referral were not significantly different between the groups at either surveillance interval.

CONCLUSION

When comparing e-EMR against p-EMR for lesions ≤25 mm in size of similar morphology in a large prospective multicenter cohort, e-EMR offered no additional advantage for predicted-benign LSLs. However, it was associated with an increased risk of major DMI. Thus, en bloc resection techniques should be reserved for lesions suspicious for invasive disease. (Clinical trial registration number: NCT01368289.).

Underwater versus conventional endoscopic resection of nondiminutive nonpedunculated colorectal lesions: a prospective randomized controlled trial (with video)

BACKGROUND AND AIMS

Incomplete resection of colorectal neoplasia decreases the efficacy of colonoscopy. Conventional resection (CR) of polyps, performed in a gas-distended colon, is the current standard, but incomplete resection rates of approximately 2% to 30% for nondiminutive (>5 mm), nonpedunculated lesions are reported. Underwater resection (UR) is a novel technique. The aim of this study was to determine the incomplete resection rates of colorectal lesions removed by UR versus CR.

METHODS

In a randomized controlled trial, patients with small (6-9 mm) and large (≥10 mm) nonpedunculated lesions were assigned to CR (gas-distended lumen) or UR (water-filled, gas-excluded lumen). Small lesions in both arms were removed with a dedicated cold snare. For CR, large lesions were removed with a hot snare after submucosal injection. For UR, large lesions were removed with a hot snare without submucosal injection. Four-quadrant biopsy samples around the resection sites were used to evaluate for incomplete resection.

RESULTS

Four hundred sixty-two eligible polyps (248 UR vs 214 CR) from 255 patients were removed. Incomplete resection rates for UR and CR were low and did not differ (2% vs 1.9%, P = .91). UR was performed significantly faster for lesions ≥10 mm in size (10-19 mm, 2.9 minutes vs 5.6 minutes, P < .0001); ≥20 mm, 7.3 minutes vs 9.5 minutes, P = .015).

CONCLUSIONS

Low incomplete resection rates are achievable with UR and CR. UR is effective and safe with the advantage of faster resection and potential cost savings for removal of larger (≥10 mm) lesions by avoiding submucosal injection. As an added approach, UR has potential to improve the cost-effectiveness of colonoscopy by increasing efficiency and reducing cost while maintaining quality. (Clinical trial registration number: NCT02889679.).

Underwater endoscopic mucosal resection without submucosal injection (UEMR) for large colorectal polyps: A community-based series

BACKGROUND

Underwater endoscopic mucosal resection without submucosal injection (UEMR) is an appealing therapy for large colorectal polyps. However, this technique is not practiced widely and there are limited data evaluating UEMR in community settings.

METHODS

The study comprised patients undergoing UEMR of large (≥20 mm) sessile colorectal lesions at a community-based center. Residual neoplasia was assessed via follow-up colonoscopy.

RESULTS

Among 264 lesions (diameter 38 ± 18 mm; range 20-110 mm) 99% were successfully resected with UEMR. Two lesions involving the cecum/IC valve required multiple sessions. There were no cases of perforation or post-polypectomy syndrome. Delayed bleeding occurred in 1.6%, all managed conservatively. Residual neoplasia was present in 5.7% and was amenable to UEMR.

CONCLUSION

This large community-based series demonstrated high efficacy and safety of UEMR for large sessile colorectal lesions. The results support UEMR as first-line therapy for these lesions.

SUMMARY

Underwater endoscopic mucosal resection without submucosal injection (UEMR) is a recently developed method that has advantages over conventional EMR for treatment of large colorectal lesions. However, UEMR is not practiced widely and there are limited data evaluating this technique in everyday practice. This large community-based series demonstrated high efficacy and safety of UEMR for large sessile colorectal lesions.

Underwater Endoscopic Mucosal Resection

Although an established standard, conventional endoscopic mucosal resection (EMR) has disseminated despite an absence of studies demonstrating the value of submucosal injection. Several consequences of poorly executed submucosal injection may increase the difficulty and risk of EMR. Underwater EMR (UEMR), an alternative resection method for colonic neoplasms, avoids the need for submucosal injections. In comparison with reported outcomes of EMR, UEMR achieves similar rates of complete resection with comparable safety, with lower rates of recurrence and fewer repeat procedures. UEMR also compares favorably with endoscopic submucosal dissection in terms of procedure time and rates of complete resection, recurrence, and complications.